How may the variation of traffic loading effect measured asphalt strains and calculated pavement service life?

Abstract

Service life testing of asphalt specimen in laboratory frequently uses a highly specified and constant load. Real roads experience a considerable distribution of both placement and size of load which leads to a variety of material responses. Fatigue criteria derived from lab tests often need a large shift factor in order to match the experience on real roads. Data from an instrumented test site in southern Sweden (E4, Eket) has been used for analysis of how the variation in load placement, load size and response direction may contribute to the shift factor. The variation in measured strains at the bottom of the AC-layer has been compared with the Swedish design code ATB Road and has been used as input to the asphalt strain criterion in this code. The results are discussed with use of other contributions to the shift factor such as healing.